Lidstrom facing the absolute best at the time? Shea Weber, Kris Letang, Zdeno Chara are more talented than Potvin's contemporaries?
The position of defenseman is unique, because it allows one to control every inch of ice. Both Potvin and Lidstrom excelled at doing that.
Both defenseman were in ideal situations. Good coaching, great teammates, ideal systems; great development. On longetivity, I would argue that Lidstrom's longetivity is much enhanced because Babcock protects him...Lidstrom has always been paired with a puck-moving defenseman who could win the board battle/take the hit in Lidstrom's pace.
It just seems that, objectively, Potvin was more effective than Lidstrom. One of the best blueline-to-blueline passers in the game's history. A physical monster. Defensively, maybe it is hockey eisegesis, but Potvin just seemed harder to beat.
Put in another way, defensively, Potvin could stop 90% of all NHLers with 90% effectiveness, and 10% with 80% effectiveness. Lidstrom could stop 98% of NHLers with 90% effetiveness, but the other 2% he'd only be 50% effective against.
Lidstrom, for example, is a little weak in front of the net, especially against big guys. If you were wizard enough, or big enough, you could finesse or bulldoze around him because he wouldn't play the body. Of course, the list of people talented enough is tiny, but still...